Engineers are constantly seeking improved performance and expanded capabilities for fuel systems, especially for those related to compression ignition engines. Numerous references show four wire systems that include first and second electrical actuators associated with each fuel injector. One of the electrical actuators typically relates to pressure control, and the other of the two electrical actuators is typically associated with controlling the needle valve member to open and close the nozzle outlet. In some common rail four wire systems, the first electrical actuator may be associated with controlling an intensifier piston to perform injections at an elevated pressure, which is greater than a pressure maintained in the common rail. The second electrical actuator relieves and applies hydraulic pressure on a needle valve member to open and close a nozzle outlet independent of controlling the intensifier. An example of such a system has been known as the Bosch APCRS fuel system. Such a system can inject fuel at a high pressure directly from the rail via the utilization of the electrical actuator for needle control alone, or inject at an even higher intensified pressure by utilizing both the needle valve actuator and a second electrical actuator associated with intensifier control.
An additional example of an intensified common rail fuel system is provided in U.S. Patent Application Publication No. 2003/0089802. Specifically, the cited reference teaches a fuel injector having a first directional control valve for triggering an injector and a second directional control valve for actuating a pressure intensifier. Both of the first and second directional control valves are actuated using a single actuating element that is coupled with the directional control valves via a shared hydraulic coupling chamber. Each directional control valve includes a neutral position and two switched positions, which may be selected via actuation of the single actuating element. Although fuel systems of this type have achieved expanded capabilities, there remains room for improving performance and reducing complexity.
The present disclosure is directed toward one or more of the problems set forth above including improving performance and/or reducing complexity in electronically controlled fuel systems.